The SILC Config util library is based on two main objects, SilcConfigFile
 (or File object) and SilcConfigEntity (or Entity).  The File objects are
 structs directly corresponding to the real files in the filesystem, while
 Entities are a little more abstract.

 An Entity is composed by delimited area on a File object (it can take the
 whole File object or just part of it), plus a group of known options.
 In order to parse this file, first you need to create a File object with
 the silc_config_open() function, and then you need to create the Entity
 with the silc_config_init() function.

 Now you can use the newly created Entity to register a group of expected
 known options and sub-blocks, and then you can call the main parsing loop
 with the silc_config_main() function. When silc_config_main() will 
 return, if some error encoured the object file will point to the file 
 that caused this error (this can be different from the originally 
 opened file if it contained `Include' directives).  If no errors 
 encoured then the File objects will still point to the original file.

 While silc_config_main() will take care of destroying Entities before
 returning, you need to take care that the File object you created is freed
 with the silc_config_close() function.

 The SILC Config library won't take care about storing the values contained
 in the config file.  You must take care about it with the callback
 functions.

 The config file syntax is pretty straightforward.  All lines starting
 with `#' will be skipped, while sub-blocks are delimited by braces (see
 the example below).

 Options with argument must have the `=' character between the option
 name and the value.  Simple words and numbers does not require quoting.
 There is a special built-in directive "Include" which allows you to include
 another config file in the point the directive is.  You can also Include
 inside a sub-block body, in this case when parsing the included config file
 it will be assumed that we are within this block, and the included file
 won't be allowed to close his root block.

 Example:

    cipher {
       name = aes-256-cbc;
       module = "aes.sim.so";
       key_length = 32;       # usually the default is just fine
       block_length = 16;
    };
    Include "/etc/silc/hash_funcs.conf";